Studies of human sleep have revealed that sleep progresses through a series of stages. The number of stages an individual has and at which stage the individual wakes up has a direct effect on how much rest the individual will have. This is a reason why sometimes an individual can sleep only a few hours and then wake up fully rested, relaxed, and ready for a new day, and then at other times, an individual can sleep for many hours and still need more rest. It is often not recognized that by setting an alarm clock for wake up, an individual can be significantly more fully rested by sleeping another 10-20 minutes less or more than the set time for wake up. This is because the sleep stage at which an individual wakes significantly affects his or her restfulness later in the day.
It is noted that about one third of a human's life is spent sleeping. It has been reported that 62% of American adults experience a sleep problem a few nights per week, and yet a small number of people will discuss their sleep problems with their doctors. In the U.S., adults sleep an average of 6.9 hours, which is slightly less than the 7-8 hours recommended by the National Sleep Foundation. This deficiency can cause 75% of American adults to have at least one symptom of a sleep problem in the past year. 25% of American adults say that they do not get the minimum amount of sleep to be alert the next day. According to the latest analysis performed by the National Heart, Lung and Blood Institute, about 70 million people in the U.S. have a sleep problem and 40 million of these are chronic. Of these, 18 million people suffer from sleep apnea. Sleep related problems cause a cost of $18 billion per year as a result of reduced work performance and productivity. There is also immense potential in pediatric sleep monitoring as it accounts for 46% of the total market and has an annual growth of about 10% in revenue every year.
Current medical research relies on recordation of brainwaves to sort or determine the stages of sleep for an individual. Such equipment for brainwave recordation requires an individual to wear an uncomfortable cap or attached multiple electrodes with several wires connected to a nearby electronics box. These brainwaves are typically recorded overnight and analyzed by a sleep specialist to sort and score the sleep performance. There have been attempts to utilize wireless transmitters to reduce the need for wire connections; however, even in that case, wearing the cap or attaching electrodes can require some set-up time and professional expertise. In addition, the cap, even without wires, can be uncomfortable, and it is not usually available for home use. Accordingly, there is a need for improved systems and techniques for determining sleep patterns.
Further, a circadian rhythm is any physiological process that displays an endogenous, entrainable oscillation of about 24 hours. These rhythms are driven by a circadian clock, and rhythms have been widely observed in people, animals, and plants. Although circadian rhythms are endogenous (“built-in” or self-sustained), they are adjusted (entrained) to the local environment by external cues called zeitgebers, commonly the most important of which is daylight. In the case of a need for adjustment of an individual's circadian rhythm, a common approach is to control the exposure of the individual to lighting. However, there is a continuing need for improved systems and techniques for determining and controlling circadian rhythms.